Yes, that's bizarre. The HD version is a little rough around the edges - but only a little. Still very playable and enjoyable. And now NightSky is the daily deal - and the HD version is still unavailable.

Yeah, the HD version was available in beta (or was it alpha?) state in one of the main Humble Bundles. I have no idea what happened with that, I found no kind of dev blog or anything for that around that time, and I didn't check if it was ever updated in the bundle.

The Humble Bundle HD version wasn't updated. I had been waiting for an update, but a few days ago decided to play it as it is - and it's actually OK. Some animations are jittery, but the game still looks good. From my perspective, it's definitely better than the low-resolution version. That's exactly why it's so bizarre that the HD version is unavailable on Steam. And the game itself is very good.

I just bought the game on Steam and was disappointed that the game ran in a very small section of my monitor even though it was set at full screen in the settings. Rather than messing about I did a bit of research and there is an updated .exe that enables the proper full screen mode. Is this the HD version? Anyway it works. Grab the updated nightsky11.exe from here http://www.ni2.se/files/games/ Copy the new nightsky11.exe over the original nightsky.exe in the steam/steamapps/common/nightsky folder and rename it back to nightsky.exe then everything works perfectly in fullscreen.

As a temporary workaround, I assume you could find the .exe for the game, right click it, go to properties and adjust the compatibility settings so that it automatically switches desktop resolution to a lower one while you play?